Our main goals are to identify, characterize, and isolate Fasciola hepatica antigens which can be used initially for the immunodiagnosis of acute and chronic fascioliasis in experimentally infected mice and rabbits and apply this knowledge to infections in humans. These antigens will also be evaluated as immunodiagnostic reagents to predict success of chemotherapy in infected humans. The antigens will be isolated and applied to sensitive immunologic assays including ELISA, RIA, and EITB, as well as others which we have shown to be highly effective for the immunodiagnosis of fascioliasis using crude antigens, like gel diffusion and counterelectrophoresis (CEP). Monospecific polyclonal and monoclonal antibodies will be developed to these antigens and used in the development of in vitro antigen purification assays like the antigen capture ELISA and to detect circulating antigens. These antigen specific probes will also aid in the dissection and study of the expression juvenile, semimature and mature antigens on the surface of the fluke.